Vertebral bone marrow fat content in normal adults with varying bone densities at 3T magnetic resonance imaging.

BACKGROUND: Sex-related differences of vertebral bone marrow fat in relation to varying bone densities have not yet been evaluated although some studies have reported an inverse association of bone marrow fat and bone mineral density (BMD). PURPOSE: To evaluate the relationship between bone marrow fat and BMD and to demonstrate the sex-related differences of the vertebral bone marrow fat in normal adults with varying bone densities. MATERIAL AND METHODS: A total of 123 normal adult volunteers were enrolled in this study. 1H-MRS of the lumbar spine was performed. The fat fraction (FF) values of vertebral bone marrow were measured. Volumetric BMD measurement was performed by quantitative computed tomography (QCT). All participants were divided into three groups according to BMD (normal, osteopenia, osteoporosis). The differences in the FF and body mass index (BMI) values of the three groups were compared, and partial correlation analysis was used to evaluate the correlation between FF values and BMD/BMI. RESULTS: The FF values increased with decreasing BMD in both male and female participants. There were significant sex differences for the FF values in the normal bone density group ( P < 0.001). The FF values of the normal bone density group in male participants were significantly higher than those of the female participants ( P < 0.001). The FF values were significantly negative correlated with BMD for all participants (r = -0.820, P < 0.001). CONCLUSION: The FF values of vertebral bone marrow correlated inversely with BMD. Sex-related differences of FF values was related to BMD.